Fallen Cake

I delivered a three-tier cake to a wedding venue yesterday. The cake was in perfect condition when I left, as the photo I took shows. Three hours later I got a call from the irate bride that the back of the cake had collapsed. The MOB told me they are cancelling the check. I have been doing this for years and never had a failure. I did notice that the venue was very warm. I also delivered 4 fudge-filled half sheet cakes to them. I feel absolutely horrible about this but don't expect to do it for free. How should I deal with them?

The first thing that jumps out at me is that the MOB said they are cancelling the check......why do they still have money outstanding? I make all my clients pay IN FULL end of, 30 days prior to delivery. This way the can't pull this kind of crap and get away with it. I'd be demanding photographic evidence but at the same time - you need to err on the side of caution just in case they are telling the truth.

My contract states that once the cake has been delivered that anything that happens to it, is not my responsibility because anything could happen when I'm not there - they could claim the back fell off and in actual fact someone ripped the back off - there would be no way to prove either way.

Situations like these are the reason I have a contract with absolutely no loop holes!